He was shot eight times, including seven times in the head, at Stockwell Tube station after officers mistook him for a suicide bomb suspect.

On the day of the shooting Sir Ian told a news conference that, as far as he understood, the shooting was directly linked to the anti-terrorist operation following the failed suicide bomb attacks on London the day before.

Scotland Yard was also quoted as saying Mr Menezes' "clothing and behaviour" added to suspicions he was a suspected suicide bomber.

We have not made any assumptions and... will try to establish the truth in an impartial, proportionate and timely way

And family lawyer Harriet Wistrich told BBC News: "We're pleased that they are now investigating that and that the home secretary has approved an investigator to look into the conduct of everyone concerned including, ultimately, Sir Ian Blair," she told BBC News.

A spokesman for the Jean Charles de Menezes Family Campaign claimed that senior Met officers had given "off the record" statements to journalists immediately after the shooting.

"We believe these off-the-record briefings were attempts to mislead the public and cover up the fact that the police had killed an innocent man," he added.

The Independent Police Complaints Commission probe will be led by senior investigator Mike Grant, and be separate from the IPCC's existing investigation into the circumstances of the shooting.

IPCC chairman Nick Hardwick said: "Neither we nor Jean Charles' family want this complaint to distract us from the main task of finding out how and why Jean Charles died.

"We still expect our investigation into the shooting to be completed by the end of December."

He added: "We have not made any assumptions and for the sake of Jean Charles' family, officers within the MPS and the public at large, will try to establish the truth in an impartial, proportionate and timely way."

'Completely right'

Meanwhile, Liberal Democrat home affairs spokesman Mark Oaten said "lessons must be learned" from the Brazilian's "tragic death".

He added that it was critical to "have confidence in the public statements of the police".

And Shami Chakrabarti, director of human rights group Liberty, told BBC News 24: "It's completely right that the media handling and the statements and the comments that were made about the shooting are dealt with just as robustly as the police operation itself."

A second aspect of the Menezes family's complaint - that Scotland Yard delayed informing it of the death - will be incorporated into the main IPCC inquiry expected to conclude by the end of the year.